In the related art, a distributed control system (DCS) has been constructed to implement an advanced automatic operation in a plant, a factory, or the like. In the DCS, field apparatuses (a measurement instrument and an actuator) and a control device for controlling the field apparatuses are connected via a communication means. Although a communication system which is the base of such a DCS mostly performs wired communication, wireless communication based on a wireless communication standard such as International Society of Automation (ISA) 100.11a has also been implemented in recent years.
In the plant and the like, safety and reliability have the highest priority. Therefore, the field apparatus which constructs the DCS usually includes a self-diagnosis function of automatically diagnosing its own status. Here, self-diagnosis to be automatically performed in the field apparatus is generally classified into self-diagnosis in which it is diagnosed whether results of measurement and arithmetic operations to be periodically performed are abnormal and self-diagnosis in which it is diagnosed whether a setting value such as a parameter is abnormal. In the former diagnosis, for example, a process value error representing that a process value has exceeded a preset threshold value or a sensor error representing that a signal from a sensor is an abnormal value is diagnosed. In the latter diagnosis, for example, an adjustment error representing that an adjustment amount set by the user to adjust the field apparatus is an abnormal value is diagnosed.
The field apparatus of the related art processes an error detected by the self-diagnosis as an alarm and saves four previously generated alarms as an alarm history. Here, the field apparatus of the related art is configured to update the alarm history only when the generated alarm has been changed without updating the alarm history when the same alarm is continuously generated. In addition, when a new alarm has been generated in a status in which four alarms are already saved as an alarm history, an oldest alarm is configured to be overwritten with the newly generated alarm.
The following Patent Document 1 does not relate to the field apparatus, but discloses technology for recording an execution command history of a central processing unit (CPU). Specifically, in Patent Document 1, technology for recording a command executed by the CPU, its address, or write data as a history on a command history buffer in order to facilitate analysis when an error which disables processing continuation is generated in an information processing device including a CPU of a pipeline control scheme is disclosed.